SSC CPO SI and ASI 2011 Paper

Question : 123 of 200

Marks: +1, -0

The speed of the current is 5 km/h. A motorboat goes 10 km upstream and back again to the starting point in 50 minutes. The speed, in km/h, of the motorboat in still water is

Validate

Solution:

(3) Let the speed of motorboat in still water be b km/h. So,

{10}/{b-5}+ {10}/{b+5}= {50}/{60}

⇒{2 b}/{b^{2}-25}= {1}/{12}

b^{2}-24 b-25=0

⇒ b=25 {km} \/ {h}

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